Merge pull request #33318 from lxxxvi/multiple_expressions_in_assert_no_difference

Documentation and some tests for `assert_no_difference`

1 files changed, 12 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/testing/assertions.rb b/activesupport/lib/active_support/testing/assertions.rb
index 6a56da384f..b27ac7ce99 100644
--- a/activesupport/lib/active_support/testing/assertions.rb
+++ b/activesupport/lib/active_support/testing/assertions.rb
@@ -113,11 +113,23 @@ module ActiveSupport
       #     post :create, params: { article: invalid_attributes }
       #   end
       #
+      # A lambda can be passed in and evaluated.
+      #
+      #   assert_no_difference -> { Article.count } do
+      #     post :create, params: { article: invalid_attributes }
+      #   end
+      #
       # An error message can be specified.
       #
       #   assert_no_difference 'Article.count', 'An Article should not be created' do
       #     post :create, params: { article: invalid_attributes }
       #   end
+      #
+      # An array of expressions can also be passed in and evaluated.
+      #
+      #   assert_no_difference [ 'Article.count', -> { Post.count } ] do
+      #     post :create, params: { article: invalid_attributes }
+      #   end
       def assert_no_difference(expression, message = nil, &block)
         assert_difference expression, 0, message, &block
       end